Slug shedder



June 22, 1 R. H. ARMACOST SLUG SHEDDER Filed April 3, 1963 IIII w V FI Y \n \\\\\\\\\\\\L I I'll ROBERT E flemncosr INVENTQR.

United States Patent 3 Claims. (Cl. 83- 128) The invention relates to a piercing punch of such design that after the punch has operated upon a workpiece the slug which has been punched out of the workpiece will be prevented from momentarily adhering to the punch and accordingly prevented from being withdrawn with the punch from the workpiece. More particularly, the invention is concerned with an expedient for positioning the slug shedding element in such a manner that it will not interfere with the sharpening of the punch when sharpening becomes necessary.

. Piercing punches have been iabricated'for a great many years and in considerable assortment, many ofwhich make no attempt to provide anything'other than a punchout device. More recently, and in order to prevent tie-ups in machinery, attention has been directed to incorporating into some piercing punches slug shedding elements designed to kick loose the slug which the piercing punch creates in its passage through the work so that the slug will always fall free through the die and not jam the operation by being pulled backwardly in company with the punch. Since punches of this kind need to be sharpened frequently in order to cut a clean hole with proper tolerance, sharpening becomes a problem when punches are equipped with slug shedding means. The most common expedient has been to disassemble the punch assembly whereby to remove the backup spring and the slug shedding mechanism while the sharpening is taking place and also where any retempering of the piercing face is being done, the device then being subsequently reassembled for use. Assembly and disassembly, however, can consume a considerable amount of time and either the machinery will be idled unnecessarily or else'a relatively large inventory will have to be stocked. of replacement punches to keep the machinery in operation while dull punches are being sharpened.

In order to minimize disassembly of composite punches of the slug shedder type, some resort has been had to a hold back means for the slug shedding element. Because of there being only a relatively small structure involved providing somewhat limited space, hold back means heretofore devised have engaged such a narrow limited area on the slug shedding element as to give a very insecure retention for the element during the sharpening operation.

The insecure hold which is the best the prior art has been able to provide has been so undependable that on a great many occasions the slug shedding element becomes dislodged popping out during the sharpening of the piercing punch and resulting in the element being cut 05 too short. a

This consequently necessitates dis-assembly of the device and substitution of a new slug shedding element. Another inadequacy in attempts to keep such a slug shedding pin in assembled condition during sharpening of the tool has resided in the fact that the backup spring continues to press against the slug shedding element with all of its initial force and hence, if there is any dislodgement whatsoever in the means provided for holding back the slug shedding element during sharpening, the slug shedding 3,190,163 Patented June 22, 1965 element tends to be immediatelypressed outwardly to an unwanted position because of the pressure of the spring always being present.

It is therefore an object of the invention to provide a new'and improved slug shedding piercing punch which is of such design that the slug shedder can be securely removed from extended position during sharpening without likelihood of being dislodged until the sharpening operation has been entirely completed.

Another object of the invention is to provide a new and improved slug shedding piercing punch which incorporates a device for securely holding the backup spring entirely out of engagement with the slug shedding element during sharpening so that there is no spring pressure to.

ing punch is'being sharpened, and if need be, while the slug shedding element is being shortened a corresponding amount.

Still another object of the invention is to provide a simple, direct and effective means of forcing the spring out of contact with the slug shedding element without it being necessary to incorporate accessory parts in a very simple piercing punch design, the device being specially secure against dislodgement while the piercing punch is being handled, placed in position for sharpening, while sharpening is taking place and until the piercing punch is ready for replacement in its operating position.

With these and other objects in view, the invention consists in the construction, arrangement and combination of the various parts of the device, whereby the oh- 7 jects contemplated are attained, as hereinafter set forth,

pointed out in the appended claims and illustrated in the accompanying drawings.

In the drawings:

FIGURE 1 is a longitudinal sectional view of the slug shedding piercing punch shown in the position it would have when ready for operation upon a workpiece.

FIGURE 2 is a longitudinalsectional view similar to FIGURE 1 but showing the piercing punch moved down wardly through a work cycle. 7 FIGURE 3 is a longitudinal sectional view of the piercing punch in inverted position preparatory tosharpening and showing the spring held in retracted position.

FIGURE 4 is a side perspective view of the piercing punch and showing the manner in which an accessory part is used to retract the spring and hold it in the desired retracted position.

In an embodiment of the invention chosen for the purpose of illustration, there is shown a slug shedding piercing punch'indicated generally by the reference character 19 designed to cooperate with a die 11 in order to punch holes from sheet material comprising a workpiece 12. The

7 from the workpiece can fall.

The slug shedding piercing punchain the chosen'embodiment consists of a spring housing 16 at the upper end 17 useful in mounting the piercing ing downwardly from the spring housing as shown in FIGURES 1 and 2 ;is a piercing punch shaft 18 which.

is an integral portion of the spring housing and is customarily of relatively smaller outside diameter.

the threaded plug 22 being provided with a hexagonal rei cess for insertion and removalof the plug when needed.

A shed-tier pin in the chosen embodiment consists of a shank 24 sli'dably positioned in the boreiZ-G having a lower end, 25' as viewed in FIGURES 1 and 2 adapted in one position as shown in FIGURE l to coincidewith a cutting face 26 of the piercing punch shaft 18. At the upper end of the'sha'nk as shown'in FIGURE 1 is a head 27, joined to the shank, the head being freely slidable in the lower end of the chamber 19. Inasmuch as the bore is appreciably smaller in diameter than the diameter-of the chamber 19, there is formed an annular shoulder 28 at the junction of the bore with the chamber.

In order. to urge the piercing pin outwardly through its slug shedding movement, there is provided a spring 29 having its upper end bearing against the plug 22 and provided at its lower end with a spring keeper 30, as shown in FIGURES 1 andZ s The spring keeper 30 has a reduced portion 31" provid-i ing a shoulder 32 for reception of the lower end of the spring; On the opposite side the keeper has an annular beveled end 33 terminating in a face 34 which is normally in engagementwith a face 35 on the adjacent-side of the head 27. Action of the spring 20 upon the spring keeper 30 tends to force the springkeeper against the,

head 27 and eject the lower end 25 of the shank 24 out wa-rdly so as to dislodge any slugpunched out by the cutting face 26'during its operation, as suggested by the arrangement of parts in FIGURE 2.

" The spring housing is provided'with a transverse hole,

36, 36 the hole being such that it pierces the wall of the.-

spring housing on diametrically opposite sides, making in effect, a hole having two parts 36 and 66. It is important to note that the location of the hole 36, 36' issuch that the lowermost edge of the hole is substantially coincident with the face 35 of the head 27 and that'the uppermost edge of the hole 36, 36' is susbtantially coincident with the uppermost edge of the annular beveled end, 33 of the spring keeper 30. v, a

7 When the piercing punch is to be sharpened it is advantageous to press the shank 24 inwardly to approximately the position shown in FIGURE 1, this inwardly press wardly from the extended position shown in FIGURE 4, for example. After the shank has been pressed inwardly,

the piercing punch shaft 18.

is then applied to the piercing punch to sharpen the cut-,

' When a, grinding wheel 39 ting face, the shank will be shortened by a corresponding amount. After sharpening the retention pin 37 isiwithdrawn and the piercing punch is then again ready for use.

Having thus described my invention, I claim: 1. A slug shedding piercing punch comprising a body having a spring housing atone end and a piercing. punch shaft at the other end terminating in a cutting face at a.

free end thereof, said spring housing having an axially extending chamber therein and saidrshaft having an axial bore therethrough in axial alignment with and in communication with said chamber and means forming ,a shoulder at the junctionof said bore with saidchamber, a shedder pin having a shank'slidably contained insaid bore and ahead for said shank located in said chamber and means on said headadapted to seat on said shoulder when the pin is in extendedsposition, a spring keeper slidably contained in:the chamber and normally in engagement with said head,.spring retaining means locatedat an end of said chamberopposi-te said bore and a spring in said chamber in engagement atone end with the keeper and at the other end with the springretain-ing means,

means forming a laterally open recess having an outer end larger, than an inner end thereof between said keeper and said head, said spring housing having a transverse ing ofthe shaft and shortening of the shedder pin.

2. A slug shedding piercing punch comprising'a body; having a spring housing at one end and a piercing punch shaft at the other end joined to and forming an integral part of said spring housing and terminating in a cutting face at a free end thereof,said spring housing'having an axially extending chamber therein and said shaft having an axial bore therethrough in axial alignment with and in communication with said chamber, said bore being+of smaller diameter than the chamber and forming a shoul-; der at the junction of {said bore with said chamber, a

shedder pin having a shank slidably contained in saidbore and a head for said shank located in said ch'amber and adapted to seat on said shoulder when the pin is inextended position, a spring keeper slidably contained in the chamber and normally in engagement with said head, ia removable plug for said chamber located at an end thereof opposite said bore and a spring in said-chamber in; engagement at one end with the'keeper and at the other end with the'plug, an an'nular beveled end on said keeper 7 at the side/thereof in engagement with saidhead, said spring housing having a transverse hole in the wall at a location'coincidentwith the inner face of the head" and as proposed, a retention pin 37 having a tapered end 38 s is inserted into thehole 36, 36 and forced inwardly with sufficient pressure to cam back the spring keeper 30 to the position shown in FIGURE 3.1 The retention pin 37 is made long enough so that it extends generously through the entire length of the transverse hole, 36, 36 and so that it can protrude from opposite sides as shown-to good advantage in FIGURE 3." Extending as described, the:

retention pin cannot readily be dislodged and accordingly ,the spring 29 and its keeper '30 are securely held back in restrained position while the slug shedding piercing pin is being handled'prepar-atory to and during the grinding as well as subsequently until it is ready for reinsertion i into the punch press.

In this typeof device grinding is bestaccomplished by mounting the piercing punch in inverted position as shown inFIGURE 3. In this orientation the slug shedder pin will fall by gravity until the head 27 rests upon the annular, beveled end of the spring keeper when the, shedder pin is in its innermost position, said hole piercing the wall of said housing on opposite sides and adapted to removably receive a retention pin at a location behind said shedder pin whereby ,to'hold the'spring 'keeper and the spring in retracted position and to block the shedder pin from movement inwardly duringsharpening of the shaft i and shortening of the shedder pin. a

3. A slug shedding piercing punch comprising abody' having a spring housing atone end and a'piercing' punch 5 shaft at the other end terminating in a cuttlng face at a a free end thereof;;said springhousing having an axiallyl extendingchamber therein and said shaft haying anax al bore therethrough in axial alignment w-ithand in com munication with said chamber'and means forming a shoulder at the'juncti'on of said bore iwith 'saidchamber', a': shedder pin having a shank slida'bly contained in said bore and a head for said shank located in said chamber and j means onsaid head adapted to seat on said shoulder when the pin is in extended position, spring retaininggmeans 3,190,160 5 6 located at an end of said chamber opposite said bore and during sharpening of the shaft and shortening of the a spring in said chamber in engagement at one end with shedder pin. the head and at the other end with the spring retaining means, means forming a laterally open'recess between References Cited by the Examiner said spring and said head, said spring housing having a 5 UNITED STATES PATENTS pair or" axially aligned transverse holes in the Wall at a 2 917,960 12/59 Gargrave location coincident with said recess when the shedder pin 31053319 11/62 Johnson g is in its innermost position, said hole being adapted to 1 12 10 Reece 3 1 removably receive a retention pin at a location behind said head whereby to hold the spring in retracted position 10 ANDREW R. JUHASZ, Primary Examiner, 

1. A SLUG SHEDDING PIERCING PUNCH COMPRISING A BODY HAVING A SPRING HOUSING AT ONE END AND A PIERCING PUNCH SHAFT AT THE OTHER END TERMINATING IN A CUTTING FACE AT A FREE END THEREOF, SAID SPRING HOUSING HAVING AN AXIALLY EXTENDING CHAMBER THEREIN AND SAID SHAFT HAVING AN AXIAL BORE THERETHROUGH IN AXIAL ALIGNMENT WITH AND IN COMMUNICATION WITH SAID CHAMBER AND MEANS FORMING A SHOULDER AT THE JUNCTION OF SAID BORE WITH SAID CHAMBER, A SHEDDER PIN HAVING A SHANK SLIDABLY CONTAINED IN SAID BORE AND A HEAD FOR SAID SHANK LOCATED IN SAID CHAMBER AND MEANS ON SAID HEAD ADAPTED TO SEAT ON SAID SHOULDER WHEN THE PIN IS IN EXTENDED POSITION, A SPRING KEEPER SLIDABLY CONTAINED IN THE CHAMBER AND NORMALLY IN ENGAGEMENT WITH SAID HEAD, SPRING RETAINING MEANS LOCATED AT 